Years ago I wrote about the different styles of
private declarations in Ruby and my personal preference. It was the best I could see at the time, but it was only marginally better than the rest and totally non-standard. Now I think I’ve finally arrived at a style that is superior to all of them.
To recap, the common style is this.
class Stuff def something_public # … end private def something_private # … end end
Despite being ubiquitous, it’s actually awful. If your file is large, the only way to know if a method you’re looking at is private or not is to keep scrolling upwards until you either see a
class declaration. All Rubyists have done this so many times now it’s become habitual. We’ve all internalized this as normal and we don’t ever think about how absurd it is. There’s a better way, though. If you’re a savvy Rubyist, you might be aware that the
private declaration doesn’t affect class methods.
class Stuff private def self.something_private # Not actually private end end
Never having tried to directly call a class method I’d declared as private, I didn’t discover this for years. To actually make a class method private you have to use
class Stuff def self.something_private # Now this is private end private_class_method :something_private end
Which led me to realize you can do the same thing with instance methods and
class Stuff def something_private # This is private end private :something_private end
And even better, the private declarations can be inlined.
class Stuff def something_public # … end private def something_private # … end private_class_method def self.classy_private # … end end
This works because the return value of a method declaration is the method name as a symbol, which gets passed as an argument to
Whatever your initial gut reaction is to the repetition, it will quickly be replaced by the surprising relief of knowing immediately whether the method you’re working on is public or private and not having to jump around to find out. I’ve been using this for the last several months and it’s great. Try it—you’ll come to love it too.